EN AW-7075 (AlZn5,5MgCu) is an aluminium alloy with a high strength. However, very poor weldability due to hot cracking susceptibility makes additive manufacturing of EN AW-7075 not feasible without additional measures.

In this study laser metal deposition (LMD) of EN AW-7075 is enhanced by addition of TiC-nanoparticles (35-55 nm) up to a content of 1 %vol.

It was found that without TiC addition the most significant problems are hot cracking and growth of coarse strongly oriented grains. These issues can be overcome by feeding TiC nanoparticles into the process. In particular, the grain size could be reduced by almost two orders of magnitude by adding 1% vol. of TiC-nanoparticles. This documents that TiC-nanoparticles that are simply stirred into the powder feedstock can be transferred into the melt pool and serve as grain refiners. The grain size decreases with increasing content of nanoparticles. Also with increasing content of nanoparticles, the fraction of globular grains increases. A homogeneous microstructure was reached at 1% vol. of TiC. Furthermore, with this proportion the number of hot cracks can be minimized, and hot cracks are reduced in length when the microstructure shows small globular grains. Moreover, even at low concentration of nanoparticles, the surface quality of the produced samples increases.